The present invention relates to the technology which can be applied effectively to a semiconductor integrated circuit (IC) including an output circuit for outputting high potential difference signals and more specifically to the technology which can be applied effectively to a liquid crystal display driving IC (liquid crystal control driver) comprising a circuit for outputting the signal supplied, for example, to a liquid crystal panel.
In recent years, as a display unit of a portable electronic apparatus such as a mobile phone and a PDA (Personal Digital Assistants), a dot matrix type liquid crystal panel, wherein a plurality of display pixels are generally arranged in two dimensions, for example, in a matrix shape, is utilized and this apparatus comprises therein a liquid crystal display controller (liquid crystal control driver IC) constituted as a semiconductor integrated circuit for controlling and driving display to this liquid crystal panel.
An internal logic circuit or the like within this liquid crystal control driver IC is usually capable of operating with a voltage as low as 5V or less, while display drive of the liquid crystal panel requires a voltage as high as 20 to 40V. Therefore, the liquid crystal control driver IC is provided with a drive circuit and an output circuit being operated with voltages boosted up from the power supply voltage, in addition to internal logic circuits being operated with voltages of 5V or less.
As is well known, a dot matrix type liquid crystal panel is provided, in addition to the signal lines to which the image signal is impressed, with scanning lines allocated in the direction crossing the signal line and sequentially driven to the selection level and provided with pixels at the intersecting points of the signal lines and scanning lines. Therefore, the liquid crystal display driving IC of the related art for driving the liquid crystal panel has been generally provided with a driving circuit (source driver) for outputting voltage applied to the signal lines (data lines) and a driving circuit (common driver) for outputting voltage applied to the scanning lines.
However, in recent years, as a TFT liquid crystal panel, those mounting a scanning line driving circuit and a data line driving circuit constituted by TFT have been provided. The liquid crystal panel of the structure explained above is disclosed, for example, in the patent document 1. The liquid crystal display driving IC for driving display of the liquid crystal panel provided with the scanning line driving circuit has the advantages that the scanning line driving circuit is no longer required and chip size can be reduced.
[Patent Document 1]
                Japanese Unexamined Patent Publication No. 2004-163600        